m-Hydroxybenzoate has been shown to serve as a growth substrate for a variety of microorganisms which hydroxylate this compound either at carbon 4 or 6 in preparation for ring cleavage as taught in J. Bacteriol. 107, 468-475 (1971); Dokl. Acad. Nauk SSR. 234, 696-698 (1977); Bull. Agr. Chem. Soc. Japan 24, 211-216 (1960); Ann. Inst. Pasteur, Paris 117, 47-57 (1969); Arch. Mikrobiol, 59, 302-314 (1967); and J. Gen. Appl. Microbiol. 4, 241-258 (1958). The enzymes which catalyze the hydroxylation of m-hydroxybenzoate to protocatechuate and gentisate have been purified from Pseudomonas testosteroni, Biochem. Biophys. Res. Commun. 55, 1102-1110 (1955), and Pseudomonas aeruginosa, Biochem. Biophys. Res. Commun. 55, 897-903 (1973), respectively.
Previously reported procedures for the bioconversion of m-hydroxybenzoate did not provide for the hydroxylation of this compound to form desired 2,3-dihydroxybenzoate which is also difficult to prepare by chemical synthesis. 2,3-Dihydroxybenzoate is a potentially useful iron-chelating drug as discussed in J. Pharmacol. Exp. Ther. 190 (3), 187-92 (1974) and Iron Metabolism. Thalassemia Conf. p. 187-192 (1975).